Fuel tank structure

ABSTRACT

A fuel tank structure has a plurality of cylindrical tank main bodies ( 4 ), a piping ( 36 ) arranged to communicate the end portions of the tank main bodies  4  from one another and a block-shaped connector portion ( 35 ) provided at the outside of the end portion of the tank main body ( 4 ). The piping ( 36 ) couples the corresponding connector portions ( 35 ) to each other and is entirely disposed to the tank main body side with respect to an end surface of the connector portion ( 35 ), which is on the opposite side to the tank main body ( 4 ) with respect to the connector portion.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a fuel tank structure for use in a vehicle using gaseous fuel such as natural gas, for example.

[0003] 2. Description of the Related Art

[0004] Conventionally, among vehicles using gaseous fuel such as natural gas, there are ones on each of which a large-size fuel tank 100 is mounted as shown in FIG. 8. The fuel tank 100 is usually configured in a cylindrical shape in order to uniformly disperse the pressure of fuel gas contained therein. Since the diameter of the fuel tank becomes large in order to secure a sufficient capacity, a large space such as a trunk room 110 is utilized as a place where the fuel tank is mounted.

[0005] A partition plate 111 is provided at the rear side of the fuel tank 100 and the rear side of the partition plate is used as a practical portion for the trunk room 110.

[0006] However, since there are many useless spaces at the mounting portion of such the cylindrical fuel tank 100 with a large diameter, there arise problems that the space utilization factor is degraded and the space within the vehicle such as the trunk room 110 is reduced to a large extent. Further, when the size of the fuel tank 100 is reduced, there arises a problem that the capacity of the fuel gas inevitably reduces.

[0007] Thus, there is proposed an example (JP-A-2000-219050) wherein the fuel tank 100 is divided into two tanks each having a relatively small diameter and the two tanks are disposed in a manner that the outer peripheral surface shapes thereof fit to the lower surface shape of a rear seat 102.

[0008] In this respect, when a fuel tank is divided into a plurality of tanks in the aforesaid manner, the plurality of tanks are required to be communicated from one another by using pipes. However, in this case, there arises a case that the space required for disposing the fuel tanks becomes large due to the pipe arrangement depending on the method of the pipe arrangement, so that the space within the vehicle is reduced. Further, there also arises a problem that the pipe arrangement is likely deformed by a shock applied from the outside depending on the method of the pipe arrangement.

SUMMARY OF THE INVENTION

[0009] Accordingly, an object of the invention is to provide a fuel tank structure which is not required to make a layout space large despite of the provision of a pipe arrangement and hardly makes the pipe deform even if a shock is applied.

[0010] In order to attain the aforesaid object, the fuel tank structure according to the first aspect of the invention has a plurality of cylindrical tank main bodies (for example, a tank main body 4 in an embodiment) each being closed at its both ends and is arranged to communicate end portions on same sides of the tank main bodies from one another by means of a pipe arrangement (for example, a piping 36 in the embodiment). A block-shaped connector portion (for example, a connector portion 35 in the embodiment) is provided at an outside of an end portion of the tank main body, and the pipe arrangement couples the corresponding connector portions to each other and is entirely disposed to a tank main body side rather than an end portion, which is on an opposite side to the tank main body with respect to the corresponding connector portion, of the corresponding connector portion.

[0011] In this manner, the block-shaped connector portion is provided at the outside of the end portion of each of the tank main bodies, and the pipe arrangement for coupling the corresponding connector portions to each other is entirely disposed to the tank main body side rather than the end portion, which is on the opposite side to the tank main body with respect to the corresponding connector portion, of the corresponding connector portion. Thus, the pipe arrangement does not protrude to the outside rather than the protruded surface of the connector portion.

[0012] Further, since the connector portion is disposed at the outside rather than the pipe arrangement, even if shock is applied from the outside to the fuel tank structure, since the shock is applied to the connector portion prior to the pipe arrangement, the shock can be prevented from being applied to the pipe arrangement.

[0013] A fuel tank structure according to the second aspect is characterized in that, in the arrangement of the first aspect, the tank main body has a cylindrical member (for example, a cylindrical member 38 in the embodiment) and a lid member (for example, a lid member 39 in the embodiment) which is provided separately from the lid member and coupled to an end portion of the cylindrical member, and the connector portion is integrally formed with the lid member.

[0014] In this manner, when the tank main body is constituted by the cylindrical member and the lid member which are formed separately, since the block-shaped connector portion is integrally formed with the lid member, it is not necessary to perform such a procedure that a connector portion provided separately from a lid member is combined with the lid member.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1 is a side sectional view showing a vehicle including a fuel tank structure according to an embodiment of the present invention;

[0016]FIG. 2 is a perspective view showing a first fuel tank of the fuel tank structure when seen from the left front side thereof;

[0017]FIG. 3 is a perspective view showing the second fuel tank of the fuel tank structure when seen from the right front side thereof;

[0018]FIGS. 4A and 4B are diagrams showing a lid member of a tank main body of the fuel tank structure, wherein FIG. 4A shows a plan view thereof and FIG. 4B shows a side view thereof;

[0019]FIG. 5 is a sectional view showing a coupling portion, in a state before coupling, between the lid member of the tank main body and a pipe arrangement in the fuel tank structure;

[0020]FIG. 6 is a sectional view showing the coupling portion, in a state after coupling, between the lid member of the tank main body and the pipe arrangement in the fuel tank structure;

[0021]FIG. 7 is a plan view showing a second fuel tank etc. of the fuel tank of the fuel tank structure; and

[0022]FIG. 8 is a side sectional view of a conventional fuel tank structure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] The fuel tank structure according to an embodiment of the invention will be explained with reference to FIGS. 1 to 7.

[0024]FIG. 1 is a side sectional view of a vehicle using natural gas, for example, to which the fuel tank structure according to the embodiment is applied.

[0025] As shown in this figure, a first fuel tank 5 is disposed at a rear side of a seat back 2 a of a rear seat 2 of a vehicle 1, and is formed by coupling a plurality of tank main bodies 4 each closed at its both ends and configured in a cylindrical shape with a small diameter. A second fuel tank 6 is disposed beneath a seat main body 2 b of the rear seat 2 and is formed by coupling a plurality of tank main bodies 4 like the first fuel tank 5.

[0026] A trunk room 10 at the rear side of the seat back 2 a is partitioned into two portions in the longitudinal direction of the vehicle by a partition plate 11 and the front side portion is used as a tank mount portion at which the tanks are mounted. The first fuel tank 5 formed so as to fit to the tank mount portion is fixed through support frames 12 to the side frames 13 of the vehicle provided so as to extend in the longitudinal direction of the vehicle.

[0027] A space between a middle cross member 14 and a rear cross member 15 each disposed so as to cross between the side frames 13 is used as a tank mount portion. The second fuel tank 6 formed so as to fit to the configuration of this tank mount portion is fixed to the middle cross member 14 and the rear cross member 15 by means of a band 17 etc.

[0028] The first fuel tank 5 is divided into a plurality of tanks, that is, specifically three divided tanks 5 a, 5 b and 5 c. These divided tanks 5 a to 5 c are coupled by joint metal members 19 in a state of being sequentially laminated thereby to form the single first fuel tank 5. Each of the divided tanks 5 a to 5 c has the tank main bodies 4 which are disposed in adjacent and parallel from one another in a zigzag manner in a state of each being elongated in a vehicle width direction, that is, a direction perpendicular to the longitudinal direction of the vehicle.

[0029] The second fuel tank 6 is divided into a plurality of tanks, that is, specifically two divided tanks 6 a and 6 b. These divided tanks 6 a and 6 b are coupled by joint metal members 20 in a state of being disposed adjacently in the longitudinal direction of the vehicle thereby to form the single second fuel tank 6. Each of the divided tanks 6 a and 6 b has the tank main bodies 4 which are disposed in adjacent and parallel from one another in a zigzag manner in a state of each being elongated in the vehicle width direction.

[0030] Here, activated charcoal etc. for absorbing gaseous fuel and storing therein is housed within the tank main bodies 4 of each of the first fuel tank 5 and the second fuel tank 6. As a result, each of the tank main bodies 4 constitutes an absorption type low-pressure gas tank.

[0031]FIG. 2 is a perspective view of the first fuel tank 5 seen from the left front side thereof.

[0032] Each of the divided tanks 5 a to 5 c constituting the first fuel tank 5 is arranged in a manner that all the tank main bodies 4 disposed in a plurality of stages in the vertical direction (specifically, three stages in each of the divided tanks 5 a, 5 b and two stages in the divided tank 5 c) are coupled and fixed from one another in a state that the end portions at the one sides along the axial line directions (specifically, the left side of the vehicle body, that is, a side shown by an arrow LH in the figure) of the respective tank main bodies are aligned.

[0033] In other words, in the divided tank 5 a, a plate member 21 a made of aluminum, for example, is attached at the left side end portions of the tank main bodies 4 so as to cross thereover, and two coupling plates 22 a, 22 a made of aluminum, for example, are attached at the intermediate areas of the tank main bodies 4 so as to cross thereover thereby to couple all the tank main bodies 4 from one another. In the divided tank 5 b, a plate member 21 b made of aluminum, for example, is attached at the left side end portions of the tank main bodies 4 so as to cross thereover, and two plates 22 b, 22 b made of aluminum, for example, are attached at the intermediate areas of the tank main bodies 4 so as to cross thereover thereby to couple all the tank main bodies 4 from one another. Further, in the divided tank 5 c, a plate member 21 c made of aluminum, for example, is attached at the left side end portions of the tank main bodies 4 so as to cross thereover, and two plates 22 c, 22 c made of aluminum, for example, are attached at the intermediate areas of the tank main bodies 4 so as to cross thereover thereby to couple all the tank main bodies 4 from one another.

[0034] These divided tanks 5 a to 5 c are coupled and fixed from one another by a joint metal member 19 in a state that the left side (the side shown by the arrow LH in the figure) end portions of the tank main bodies 4 thereof are aligned. Incidentally, in the divided tanks 5 a to 5 c, the length to the right side end portion in each of the tank main bodies 4 is determined in accordance with a space to be disposed.

[0035] Here, the inner portions of the tank main bodies 4 of the divided tank 5 a are communicated from one another through not-shown communication paths formed within the plate member 21 a for coupling the respective tank main bodies. Similarly, the inner portions of the tank main bodies 4 of the divided tank 5 b are communicated from one another through not-shown communication paths formed within the plate member 21 b for coupling the respective tank main bodies. Also, the inner portions of the tank main bodies 4 of the divided tank 5 c are communicated from one another through not-shown communication paths formed within the plate member 21 c for coupling the respective tank main bodies.

[0036] At the predetermined one of the tank main bodies 4 of the divided tank 5 a at the lower stage and the predetermined one of the tank main bodies 4 of the divided tank 5 b at the middle stage, an external pipe arrangement portion 25 is provided at the outside of the end portions of these predetermined tank main bodies in the axial line direction so as to couple the end portions on the same side of these predetermined tank main bodies which are aligned in the axial line direction. Since the inner portions of these tank main bodies 4 are communicated to each other by the external pipe arrangement portion 25, the divided tank 5 a and the divided tank 5 b are placed in a communicated state to each other. Further, at another predetermined one of the tank main bodies 4 of the divided tank 5 b at the middle stage and the predetermined one of the tank main bodies 4 of the divided tank 5 c at the upper stage, an external pipe arrangement portion 26 is provided at the outside of the end portions of these predetermined tank main bodies in the axial line direction so as to couple the end portions on the same side of these predetermined tank main bodies which are aligned in the axial line direction. Since the inner portions of these tank main bodies 4 are communicated to each other by the external pipe arrangement portion 26, the divided tank 5 b and the divided tank 5 c are placed in a communicated state to each other. As a result, all the divided tanks 5 a to 5 c are placed in a communicated state by these external pipe arrangement portions 25, 26 there by to constitute the first fuel tank 5.

[0037] Further, at the outside of the end portion on the same side of another predetermined one of the tank main bodies 4 of the divided tank 5 a at the lower stage, an external pipe arrangement portion 27 is provided so as to be coupled to the second fuel tank 6 thereby to form a communication path to the second fuel tank 6 (in FIG. 2, only a part of the first fuel tank 5 side is shown). The first fuel tank 5 and the second fuel tank 6 are communicated to each other by the external pipe arrangement portion 27 thereby to constitute the fuel tank 30 for the vehicle 1.

[0038]FIG. 3 is a perspective view of the second fuel tank 6 seen from the right front side thereof.

[0039] As shown in this figure, each of the divided tanks 6 a and 6 b constituting the second fuel tank 6 is arranged in a manner that the tank main bodies 4 disposed in a plurality of stages in the vertical direction (specifically, three stages) are coupled and fixed from one another in a state that the end portions at the one sides along the axial line directions (specifically, the right side of the vehicle body, that is, a side shown by an arrow RH in the figure) of the respective tank main bodies are aligned. Specifically, in the divided tank 6 a, a plate member 31 a made of aluminum, for example, is attached at the right side end portions of the tank main bodies 4 so as to cross thereover, and two coupling plates 32 a, 32 a made of aluminum, for example, are attached at the intermediate areas of the tank main bodies 4 so as to cross thereover thereby to couple and fix all the tank main bodies 4 from one another. Similarly, in the divided tank 6 b, a plate member 31 b made of aluminum, for example, is attached at the right side end portions of the tank main bodies 4 so as to cross thereover, and two coupling plates 32 b, 32 b made of aluminum, for example, are attached at the intermediate areas of the tank main bodies 4 so as to cross thereover thereby to couple all the tank main bodies 4 from one another. These divided tanks 6 a and 6 b are coupled and fixed to each other by a joint metal member 20 in a state that the right side (the side shown by the arrow RH in the figure) end portions of the tank main bodies 4 thereof are aligned. Incidentally, in the divided tanks 6 a and 6 b, the length to the left side end portion in each of the tank main bodies 4 is determined in accordance with a space to be disposed.

[0040] Here, the inner portions of the tank main bodies 4 of the divided tank 6 a are communicated from one another through not-shown communication paths formed within the plate member 31 a for coupling the respective tank main bodies. Similarly, the inner portions of the tank main bodies 4 of the divided tank 6 b are communicated from one another through not-shown communication paths formed within the plate member 31 b for coupling the respective tank main bodies.

[0041] At the predetermined one of the tank main bodies 4 of the divided tank 6 a and the predetermined one of the tank main bodies 4 of the divided tank 6 b, an external pipe arrangement portion 33 is provided at the outside in the axial line direction of the end portions of these predetermined tank main bodies so as to couple the end portions on the same side of these predetermined tank main bodies which are aligned in the axial line direction. Since the inner portions of these tank main bodies 4 are communicated to each other by the external pipe arrangement portion 33, the divided tank 6 a and the divided tank 6 b are placed in a communicated state to each other thereby to constitute the second fuel tank 6. Further, at the outside of the end portion on the same side of another predetermined one of the tank main bodies 4 of the divided tank 6 a, the external pipe arrangement portion 27 is provided so as to be coupled to the first fuel tank 5 thereby to form a communication path to the first fuel tank 5 (in FIG. 3, only a part of the second fuel tank 6 side is shown)

[0042] Next, the aforesaid external pipe arrangement portions 25, 26 and 33 will be explained mainly with reference to FIGS. 4 to 7.

[0043] As described above, each of the external pipe arrangement portions 25, 26 and 33 serves to communicate to each other the end portions aligned in the axial direction as to the cylindrical tank main bodies 4 which have end portions aligned in the axial direction and are disposed in parallel from one another. To this end, each of the external pipe arrangement portions includes block-shaped connector portions 35 provided respectively at the outsides in the axial line direction of the end portions of the respective tank main bodies 4 to be communicated to each other and a pipe-shaped piping 36 for coupling the corresponding connector portions 35 to each other.

[0044] Here, as shown in FIGS. 2 and 3, each of the tank main bodies 4 includes a cylindrical member 38 of a hollow cylindrical shape made of extruded aluminum and lid members 39 each formed by cutting aluminum material which are joined at the both opening portions of the cylindrical member 38 thereby to close the cylindrical member. As shown in FIGS. 4A and 4B, each of the connector portions 35 of the external pipe arrangement portions 25, 26 and 33 is configured in a block shape and formed integrally with the predetermined lid member 39 as a single unit.

[0045] The lid member 39 formed integrally with the connector portion includes a lid member main body portion 42 with a step which is combined with the cylindrical member 38 by fitting a fitting portion 41 formed on the one side in the axial line direction to the opening portion at the one end of the cylindrical member 38. The connector portion 35 protrudes in an opposite side of the fitting portion 41 so as to be positioned within the inside of the lid member main body portion 42 in a radial direction thereof and is formed integrally with the block-shaped connector portion 35. At the position in the center axial line direction of the lid member 39, a communication hole 43 is formed from the fitting portion 41 side to the predetermined intermediate portion of the connector portion 35. At the end portion of the communication hole 43 in the opposite side of the fitting portion 41, a communication hole 44 is formed so as to extend to the outside along the radial direction of the lid member main body portion 42. These communication holes 43 and 44 communicate within the tank main body 4. The outside opening side of the communication hole 44 is formed as an internal thread portion 45. An end surface 46 of the connector portion 35 on the opposite side with respect to the lid member main body portion 42 is in parallel to the lid member main body portion 42. The lid member 39 is formed in the aforesaid configuration through the cutting process etc. of the same material.

[0046] As shown in FIG. 5, the piping 36 includes a bolt member 48 to be engaged with the internal thread portion 45 of the connector portion 35 of the lid member 39. The bolt member 48 is configured in a manner that the both sides thereof in the axial line direction are formed as external thread portions 49, 50, a portion between these external thread portions 49, 50 is formed as an input portion 51 of a hexagonal column shape, and a through hole 52 is formed along the center axial line. A seal ring 53 is provided at the outer periphery of the boundary portion between the external thread portion 49 and the input portion 51 on the coupling side to the connector portion 35 of the bolt member 48. The seal ring 53 serves to seal a space at the joint portion between the connector portion 35 and the bolt member 48 at the time of engaging the connector portion to the bolt member. An annular seal groove 55 is formed at the end surface on the other external thread portion 50 side of the bolt member 48 and a seal ring 56 is provided at the annular seal groove 55.

[0047] The piping 36 further includes a piping main body 57 for coupling the tank main bodies 4 to each other by coupling a pair of the bolt members 48. The piping main body 57 has coupling portions 58 to been gaged with the bolt members 48 at the both ends thereof. That is, the piping main body 57 includes a pipe member 61 formed by stainless steel, for example, which center portion is formed by a cylindrical pipe portion 59 and which end portions are each formed by a flange portion 60 protruding outside in the radial direction; a spacer 62 of an almost cylindrical shape formed by stainless steel, for example, which makes the pipe portions 59 of the pipe member 61 at the inside thereof and abuts against the flange portion 60; and a nut member 63 of a hexagonal column shape capable of inserting the member 59 of the pipe member 61 therein. The flange portion 60, the spacer 62 and the nut member 63 constitute the coupling portion 58. The spacer 62 is provided with an annular convex portion 65 on the flange portion 60 side protruding outward in the radial direction. The nut member 63 is provided with an internal thread portion 66 on the one side thereof in the axial line direction on the inner peripheral side thereof and is provided with an annular convex portion 67 protruding inward in the radial direction at the end portion on the opposite side in the axial line direction.

[0048] In the case of coupling the tank main bodies 4 to each other by using the external pipe arrangement portions 25, 26 and 33 thus configured, as shown in FIG. 5, the bolt member 48 is precedingly meshed at its external thread portion 49 with the internal thread portion 45 of the connector portion 35 of each the tank main body 4 to be coupled in a state that the seal ring 53 is disposed between the external thread portion 49 and the internal thread portion 45.

[0049] The seal ring 56 is disposed in the seal groove 55 of the bolt member 48 in a state of being meshed with the connector portion 35 of the one tank main body 4. Then, as shown in FIG. 6, the nut member 63 of the coupling portion 58 at the one side of the piping main body 57 is meshed at its internal thread portion 66 with the external thread portion 50 of the bolt member 48. The annular convex portion 67 of the nut member 63 which moves toward the bolt member 48 with the meshing operation of the internal thread portion 66 abuts against the annular convex portion 65 of the spacer 62 thereby to move the annular convex portion in the same direction. As a result, the spacer 62 pushes the flange portion 60 of the pipe member 61 against the seal ring 56 thereby to compress and deform the seal ring 56. Consequently, the piping main body 57 is coupled with the connector portion 35 through the bolt member 48 while the seal ring 56 seals a space at the joint portion between the piping main body 57 and the bolt member 48.

[0050] Similarly, the coupling portion 58 at the other side of the piping main body 57 is coupled through the seal ring 56 to the bolt member 48 in a state of being meshed with the connector portion 35 of the other tank main body 4. When the both end portions of the piping main body 57 are coupled to the connector portions 35 through the bolt members 48 in this manner, respectively, both the tank main bodies 4 are coupled to each other through the communication holes 43, 44 of the connector portions 35, the through holes 52 of the bolt members 48 and the inner periphery of the pipe member 61, that is, the inner periphery of the piping 36.

[0051] As shown in FIG. 2, as to each of the external pipe arrangement portion 25 for communicating the tank main body 4 of the divided tank 5 a with the tank main body 4 of the divided tank 5 b in the first fuel tank 5 and the external pipe arrangement portion 26 for communicating the tank main body 4 of the divided tank 5 b with the tank main body 4 of the divided tank 5 c in the first fuel tank 5, the bolt members 48 of the corresponding connector portions 35 are directed in the same direction and the piping main body 57 of an almost U-shaped bent configuration which is adjusted to the arrangement of these bolt members is coupled to the corresponding connector portions 35, respectively. Further, as shown in FIG. 3, as to the external pipe arrangement portion 33 for communicating the tank main body 4 of the divided tank 6 a with the tank main body 4 of the divided tank 6 b in the second fuel tank 6, the bolt members 48 of the corresponding connector portions 35 are directed in the opposite directions and shifted elevationally and the piping main body 57 of a bent configuration which is adjusted to the arrangement of these bolt members is coupled to the corresponding connector portions 35, respectively.

[0052] Like the external pipe arrangement portions 25, 26 and 33, the external pipe arrangement portion 27 for communicating the first fuel tank 5 with the second fuel tank 6 includes the block-shaped connector portions 35 provided at the outsides of the end portions of the tank main bodies 4 to be communicated to each other, the bolt members 48 to be meshed with the connector portions 35 and the piping 36 for coupling the corresponding bolt members 48 by means of the coupling portions 58.

[0053] In this embodiment, as to each of the external pipe arrangement portion 25 for communicating the divided tank 5 a with the divided tank 5 b in the first fuel tank 5, the external pipe arrangement portion 26 for communicating the divided tank 5 b with the divided tank 5 c in the first fuel tank 5 and the external pipe arrangement portion 33 for communicating the divided tank 6 a with the divided tank 6 b in the second fuel tank 6, the piping 36 in a state that the connector portions 35 are coupled to each other, that is, the bolt member 48 and the piping main body 57 are entirely disposed on a the tank main body 4 side rather than the end surface (end portion) 46, which is on the opposite side to the tank main body 4 with respect to the connector portion 35, at each of the both connector portions 35 which are coupled by the piping 36. For example, FIG. 7 shows the external pipe arrangement 33 for communicating the divided tank 6 a with the divided tank 6 b in the second fuel tank 6 arranged in this manner.

[0054] As described above, the piping 36 for coupling the block-shaped connector portions 35 to each other, that is, the bolt member 48 and the piping main body 57 are entirely disposed to the tank main body 4 side rather than the end surface of the connector portion 35, which is on the opposite side to the tank main body 4 with respect to the connector portion. Thus, the piping 36 does not protrude to the outside rather than the protruded surface of the connector portion 35. Accordingly, the space for the fuel tank structure is not required to make larger due to the piping 36.

[0055] Further, the connector portion 35 is disposed at the outside rather than the piping 36, that is, the bolt member 48 and the piping main body 57. Thus, even if shock is applied from the outside to the fuel tank structure, since the shock is applied to the connector portion 35 prior to the piping 36, the shock can be prevented from being applied to the piping 36. Accordingly, the piping 36 can be scarcely deformed even if a shock is applied from the outside.

[0056] In addition, in the case where the tank main body 4 is constituted by the cylindrical member 38 and the lid members 39 which are formed separately from the cylindrical member 38, since the block-shaped connector portion 35 is integrally formed with the lid member 39, it is not necessary to perform such a procedure that a connector portion provided separately from a lid member is combined with the lid member. Thus, in addition to that such a combining procedure can be eliminated, another procedure can also be eliminated that the joint surface of a lid member is subjected to the machine working with a high processing accuracy in order to combine a connector portion provided separately from the lid member with the lid member. As a result, the manufacturing cost can be reduced. Further, since it is not necessary to secure the intensity of a screw hole for combining which is required in the case of combining a connector portion provided separately from a lid member, so that the thickness of the lid member main body portion 42 of the lid member 39 can be made smaller and the weight thereof can be reduced.

[0057] Incidentally, although the aforesaid embodiment is explained as to the case where the aforesaid configuration is applied to the external pipe arrangement portion for communicating the divided tanks from one another, the invention may be modified in a manner that an external pipe arrangement portion is used for merely communicating the respective tank main bodies and the aforesaid configuration is applied to the external pipe arrangement portion or in a manner that the aforesaid configuration is applied to an external pipe arrangement portion for communicating the first fuel tank and the second fuel tank.

[0058] While only certain embodiments have been specifically described herein, but it will apparent that numerous modifications may be made thereto without departing from the spirit and scope of the invention.

[0059] As described above, according to the fuel tank structure of the first aspect of the invention, the block-shaped connector portion is provided at the outside of the end portion of each of the tank main bodies, and the pipe arrangement for coupling the corresponding connector portions to each other is entirely disposed to the tank main body side rather than the end portion, which is on the opposite side to the tank main body with respect to the corresponding connector portion, of the corresponding connector portion. Thus, the pipe arrangement does not protrude to the outside rather than the protruded surface of the connector portion. Accordingly, the space for the fuel tank structure is not required to make larger due to the pipe arrangement.

[0060] Further, since the connector portion is disposed at the outside rather than the pipe arrangement, even if shock is applied from the outside to the fuel tank structure, since the shock is applied to the connector portion prior to the pipe arrangement, the shock can be prevented from being applied to the pipe arrangement.

[0061] According to the fuel tank structure of the second aspect of the invention, in the case where the tank main body is constituted by the cylindrical member and the lid members which are formed separately from the cylindrical member, since the block-shaped connector portion is integrally formed with the lid member, it is not necessary to perform such a procedure that a connector portion provided separately from a lid member is combined with the lid member. Thus, in addition to that such a combining procedure can be eliminated, another procedure can also be eliminated that the joint surface of a lid member is subjected to the machine working with a high processing accuracy in order to combine a connector portion provided separately from the lid member with the lid member. As a result, the manufacturing cost can be reduced. Further, since it is not necessary to secure the intensity of a screw hole for combining which is required in the case of combining a connector portion provided separately from a lid member, so that the thickness of the lid member can be made smaller and the weight thereof can be reduced. 

What is claimed is:
 1. A fuel tank structure comprising: a plurality of cylindrical tank main bodies, each being closed at both end portions thereof; a piping arranged to communicate the end portions on same sides of the tank main bodies from each other; and at least two block-shaped connector portions, each being located at an outside of the end portion of the tank main body, wherein the piping couples the connector portions to each other, and wherein the piping is entirely disposed to a tank main body side with respect to an end portion of the connecting portion, which is an opposite side to the tank main body.
 2. The fuel tank structure according to claim 1, wherein the tank main body has a cylindrical member and a lid member which is formed separately from the cylindrical member and coupled to an end portion of the cylindrical member, and wherein the connector portion is integrally formed with the lid member.
 3. The fuel tank structure according to claim 1, wherein the connector portion defines a communication hole which communicates with the piping, and the communication hole extends in a direction perpendicular to an axial direction of the tank main body.
 4. The fuel tank structure according to claim 1, wherein the piping comprises a piping main body having a pipe member and a nut into which the pipe member is inserted, and a bolt member having one end engageable with the connector portion and the other end engageable with the nut, and wherein the bolt member and the piping main body are entirely disposed to the tank main body side with respect to the end portion of the connecting portion, which is the opposite side to the tank main body.
 5. A fuel tank structure comprising: a plurality of cylindrical tank main bodies, each being closed at both end portions thereof and having a cylindrical member and a lid member which is formed separately from the cylindrical member and is coupled to an end portion of the cylindrical member; at least two block-shaped connector portions, each being located at an outside of the end portion of the tank main body; and a piping coupled with the connecter portions for communicating between the tank main bodies; and wherein the connector portion is integrally formed with the lid member as a single member. 